Mobile crane outrigger assembly

ABSTRACT

A mobile crane for use, for example, on structurally weak ship loading docks comprises an outrigger assembly attached to the mobile crane chassis for supporting the crane. The outrigger assembly has two sections, one on each side of the chassis, and each section comprises two outrigger beams, a transfer beam component attached to the outrigger beams, a pair of equalizer beam components connected beneath and near the ends of the transfer beam component at predetermined vertical reaction points, and a pair of float components (outrigger pads) connected beneath and near the ends of each equalizer beam component. A resilient bearing assembly with an integral mechanical connection for tension reactions provides an articulated connection between each component and comprises a resilient member that transmits vertical forces between components so that they are evenly distributed.

Sept. 4, 1973 MOBILE CRANE OUTRIGGER ASSEMBLY [75 Inventors: Robert C. Rosenberg, Milwaukee,

Wis.; Arick S. Malkiel, New York, N.Y.

[73] Assignee: Harnischfeger Corporation, Milwaukee,Wis.

[22] Filed: Dec. 27, 1971 21] Appl. No.: 212,332

[52] U.S. Cl. 212/145 [51] Int. Cl. B66c 23/80 [58] Field of Search 212/145 [56] References Cited UNITED STATES PATENTS 3,227,287 1/1966 Butcher 212/145 3,545,627 12/1970 Le Toumeau 212/145 FOREIGN PATENTS OR APPLICATIONS Primary Examiner-Evon C. Blunk Assistant ExaminerJames L. Rowland Attorney-James E. Nilles 5 7 ABSTRACT A mobile crane for use, for example, on structurally weak ship loading docks comprises an outrigger assembly attached to the mobile crane chassis for supporting the crane. The outrigger assembly has two sections, one on each side of the chassis, and each section comprises two outrigger beams, a transfer beam component attached to the outrigger beams, a pair of equalizer beam components connected beneath and near the ends of the transfer beam component at predetermined vertical reaction points, and a pair of float components (outrigger pads) connected beneath and near the ends of each equalizer beam component. A resilient bearing assembly with an integral mechanical connection for tension reactions provides an articulated connection between each component and comprises a resilient member that transmits vertical forces between components so that they are evenly distributed.

6 Claims, 6 Drawing Figures 1,251,928 10/1967 Germany 212/145 minnow 4:915

3,758.4 SHEET 1 [IF 2 24 PATENTEDSEP 4am I 3756424 SHEH 2 0F u /M X I MOBILE CRANE OUTRIGGER ASSEMBLY BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to outrigger assemblies for supporting mobile cranes and to bearing assemblies for such outrigger assemblies.

2. Description of the Prior Art Some mobile cranes for handling cargoes on ship loading docks comprise an upper crane unit (including a boom) which is rotatably mounted on a lower crane unit, such as a crane carrier chassis. Such cranes usually include an outrigger assembly, typically comprising four relatively small flat-bottomed floats or outrigger pads arranged in a rectangular pattern around the crane, that can be positioned so as to contact the dock surface and support and stabilize the crane during cargo handling operations. Due to space limitations on the docks such cranes are relatively narrow for maneuverability. Rotation of the upper crane unit causes shifting of the center of gravity of the crane, and high localized forces are transmitted to the dock by the floats as the crane is operated. Many older clocks are constructed of timber and wooden pilings and are generally in weak structural condition. Therefore, application of such large forces to relatively small or localized surface areas on such docks by prior art outrigger assemblies may result in damage to the docks (and some times to crane and cargo) or impose limitations on crane usage as regards to cargo weight or crane position. It is desirable, therefore, to provide improved mobile cranes and outrigger assemblies therefor which overcome the aforedescribed problems and have other advantages.

SUMMARY OF THE INVENTION A mobile crane well adapted for use, for example, on structurally weak ship loading docks comprises a rotatable upper crane unit (including a boom) mounted on a mobile lower crane unit, such as a carrier chassis. An outrigger assembly attached to the lower crane unit and movable from an extended raised, transport position to an extended, lowered position wherein it supports the crane, is comprised of two sections, one on each side of the carrier. Each section is comprised of a pair of telescoping, extendable outrigger beams which are attached at their outer ends to an extended rigid transfer beam component. A pair of float assemblies, each comprised of an elongated rigid equalizer beam component and a pair of float components are connected to and beneath the transfer beam component near the ends therof at predetermined vertical reaction points. Each float component (outrigger pad) has a realtively large surface area and is connected to and beneath the equalizer beam component near the ends thereof.

Each connection is made by means of a bearing assembly which allows for limited articulation in all directions between the oonnected components. Each bearing assembly includes a resilient member, such as an elastomeric block, for transferring forces downwardly from one component to the one below it. Each bearing assembly further includes mechanical connecting means for lifting.

The inherent design of the crane is such that the centers of gravity describe a non-circular path around th center of rotation of the upper crane unit as the latter rotates, assuming a given load and constant boom angle. However, the components of the outrigger assembly are chosen, arranged and proportioned in accordance with the invention so that each of the four connection points between the two transfer beams and their four assoicated equalizer beams serves as a load support or vertical reaction point at which the vertical reaction force will be equal (assuming a given load and a constant boom angle) when the upper crane unit is rotated in the same relative position with respect to each of the vertical reaction points. More specifically, when the center line of the boom is aligned with the end of an outrigger beam, the maximum downward force is exerted on the nearest vertical reaction point on the transfer beam. However, there is assumed to be no downward force exerted at the diametrically opposite vertical reaction point. The two remaining vertical reaction points transfer the remaining forces which are individually less than that exerted at the vertical reaction point nearest the boom centerline.

In a preferred embodiment of the invention, a mobile carrier chassis on which the lower portion of the crane is mounted is about 45 feet long and about 12 feet wide. One set of outrigger beams is connected near the rear end of the chassis and the other near the middle of the chassis, i.e., about 23 feet apart. The distance between the two transfer beams, each of which is about 32 feet long, when the outrigger beams are fully extended is about 28 feet. The distance between the attachment points, i.e., the vertical reaction points for the two equalizer beams on each transfer beam is about 30 feet. The distance between the attachment points for the two floats associated with each equalizer beam is about 15 feet. Each float is about l5 feet long, and about 5 feet wide and has a surface area of about square feet. Thus, the surface area of four floats on one side of the crane is approximately 300 square feet, and the total surface area of all floats in the outrigger assembly is about 600 square feet; or approximately six to 10 times the float surface area of comparable prior art outrigger assemblies.

The components of the outrigger assembly in accordance with the invention are relatively heavy in order to eliminate excessive deflection and, therefore, serve as an additional counterweight, thereby increasing the lifting capacity of the crane.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of a mobile crane incorporating an outrigger assembly in accordance with the invention shown on a dock or pier with a ship alongside;

FIG. 2 is a top plan view of the crane and outrigger assembly shown in FIG. 1;

FIG. 3 is an enlarged rear elevation view, with portions removed for clarity, of the outrigger assembly taken on line3-3 of FIG. 1;

FIG. 4 is an enlarged side elevation view of the outrigger assembly taken on line 4-4 of FIG. 2;

FIG. 5 is an enlarged cross-section view of one of a plurality of bearing assemblies of the outrigger assembly taken on line 5-5 of FIG. 4; and

FIG. 6 is an enlarged plan view of a portion of a float with a portion broken away to show details.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIGS. 1 and 2, a mobile truck crane 10 comprising a lower crane unit or carrier 12 on which an upper crane unit 14 is rotatably mounted and to which an outrigger assembly 16 is attached is shown on a typical dock 18 with a ship 20 alongside.

Upper crane unit 14 comprises an enclosure 22 for crane machinery, an operator's cab 24, a vertically pivotable boom 26, rigging 28 which supports the boom, and a load hoist line 30 reeved over a sheave 32 at the outer end of the boom for handling a load 34. Upper crane unit 14 is rotatable through 360 in either direction about a point or center of rotation 36, shown in FIG. 2, and is shown rotated to a position 90 to the left of the longitudinal centerline of carrier 12.

Lower crane unit or carrier 12, which for example, is about 45 feet long and 12 feet wide, comprises a chassis 38, transport wheels 40, and a drivers cab 42.

It is to be understood that the inherent design of crane is such that its center of gravity (designated as point 43 in FIG. 2) describes a non-circular path shown as a broken line 45 in FIG. 2) around the center of rotation 36, as upper crane unit 14 rotates with a given load thereon and with a constant boom angle. This is because carrier 12 is long and narrow and because upper crane unit 14 assumes various positions with respect to the carrier.

Outrigger assembly 16, which comprises a right side section 44 and a left side section 46, is movable from an extended raised transport position to a lowered position in which it is shown in FIGS. 1 and 2 and wherein it supports crane l0. Outrigger assembly 16 is comprised of outrigger beam means including four hydraulically operated telescopic outrigger beams designated as the left front and right front beams 48 and 50 and the left rear and right rear beams 52 and 54. Front beams 48 and 50, which are slightly offset from each other, are located near the middle of carrier 12 and rear beams 52 and 54, which are slightly offset from each other, are located near the rear of the carrier. The rear beams 52 and 54 are shown in detail in FIG. 3 and, for illustrative purposes, the left rear beam 52 is shown in raised extended position, while the right rear beam 54 is shown in fully extended lowered position. Left rear beam 52 is typical of the beams 48, 50 and 54 and its description will suffice for the other three. Beam 52 comprises a relatively fixed hollow box 56 which is pinconnected on the underside of and athwart the chassis 38 of carrier 12. Beam 52 further comprises a relatively movable extendable beam section 60 which telescopes into box 56 and is also movable outwardly therefrom to partially or fully extended position. In fully extended position, the outer end of beam 52 is about 14 feet from the fore and aft centerline of carrier 12. Extendable section 60 is movable to its retracted and extended positions by means of a hydraulic actuator 62 which is connected between outrigger box 56 and outrigger beam section 60. In extended position, beam section 60 is pivotable downward about a pivot pin 64 mounted inside box 56 by means of a hydraulic actuator 66 which is connected between box 56 and carrier 12. A detailed description of a type of outrigger beam adaptable for use with the present invention is provided in U. S. Pat. No. 3,073,458, granted Jan. 15, 1963 to J. E. Wieschel for Powered Outrigger Beams for Vehicles" and assigned to the assignee of the present invention.

As FIG. 2 shows, the outrigger beams 50 and 54 on the right side of carrier 12 are part of the right side section 44 of outrigger assembly 16 and outrigger beams 48 and 52 are part of the left side section 46. Since sections 44 and 46 are similar in construction and mode of operation, only right side section 44 is described in detail hereinafter.

Referring to FIGS. 1, 2, 3 and 4, the right side outrigger beams 50 and 54 are connected at their outermost ends to transfer beam means including an elongated rigid transfer beam 70 in the form of a box beam about 32 feet long. Right front beam 50 is connected at a location about 6 feet from the front end of transfer beam 70 and right rear beam 54 is connected at a location about 2 feet from the rear end of the transfer beam. These two locations are spaced about 23 feet apart.

As FIG. 3 shows, the means for connecting right rear outrigger beam 54 to transfer beam 70 comprise a hollow cylindrical bearing sleeve 72 rigidly connected to and extending through the transfer beam. A cylindrical shaft 74 which is rigidly connected to the outermost end of outrigger beam 54 is joumaled in sleeve bearing 72. A thrust washer 76 is disposed on shaft 74 between the inner side of transfer beam 70 and the outer end surface of outrigger beam 54. A keeper plate 78 is bolted to the outer end surface of shaft 74. Each of the other outrigger beams 48, 50 and 52 is understood to be connected by similar means to its associated transfer beam. This arrangement permits a very limited amount of play or relative movement between the outrigger beams and their associated transfer beams. However, when the outrigger beams are secured in extended lowered position, each transfer beam is in effect rigidly connected to lower crane unit 12 and responds to movement thereof.

Transfer beam 70 is connected at locations or vertical reaction points about one foot from each end thereof to the midpoint of equalizer beam means in the form of a pair of elongated rigid equalizer beams 80 and 82; each having the form of a boxbeam about 17 feet long and located below the transfer beam.

Right front equalizer beam 80 is connected at locations about one foot from each end thereof to the midpoints of a pair of rigid floats or outrigger pads 84 and 86 disposed therebelow. Equalizer beam 80 and its two floats 84 and 86 comprise a float assembly and all four float assemblies in outrigger assembly 16 are identical.

Right rear equalizer beam 82 is connected at locations about one foot from each end thereof to the midpoints of a pair of rigid floats 88 and 90 disposed therebelow.

Referring to FIGS. 1, 2, 3, 4 and 6, right rear float 90, which is typical of the seven other floats in outrigger assembly 16 is on the order of 5 feet wide and 15 feet long and comprises, for example, a rectangular steel upper plate 92 having a plurality of spaced, parallel steel beam members 94 welded or otherwise secured to the underside thereof. Heavy wooden crib members 96 are secured athwart the steel beam members 94 and lighter wooden crib members 98 are secured athwart the latter.

As FIG. 2 shows, left side section 46 of outrigger assembly 16 comprises a transfer beam 100, two equalizer beams 102 and 104, and four floats 106, 108, and 112.

Referring to FIGS. 3, 4 and 5, a plurality of bearing assemblies, each designated by the numeral 114, are provided at the connection points between each float and its associated equalizer beam and between each equalizer beam and its associated transfer beam of right hand section 44 of outrigger assembly 16. It is to be understood that similar bearing assemblies are provided at corresponding locations in the left hand section 46 of outrigger assembly 16. Each bearing assembly 114 serves two main functions. First, it comprises elements which serve as a means for mechanically securing a float component to an equalizer beam component or an equalizer beam component to a transfer beam in an articulated manner so that the components are relatively movable with respect to each other in all directions at least to a limited degree. Thus, the components are held in proper relationship and also can be lifted together when outrigger assembly 16 is raised. Second, bearing assembly 114 comprises a resilient member which serves as a means whereby one component can be resiliently supported by the component below it. Or, to put it another way, the bearing assembly serves as a means for transmitting forces vertically from one component to that below it. As FIG. 5 shows, bearing assembly 114 comprises a pair of spaced apart rigid steel plates 116 and 118 between which a resilient member 121, such as an elastomeric block, is disposed and, preferably, to which it is bonded. The plates 116 and 118 are adapted by a plurality of bolts 120 therein to be rigidly attached to their associated components, i.e., to a transfer beam and an equalizer beam or to an equalizer beam and a float. The plates 116 and 118 and resilient member 121 are provided with centrally located openings 122, 124 and 126, respectively, which accommodate a cylindrical steel rod bolt 128 extending therethrough. The ends of rod bolt 128 are threaded and nuts 130 and 132 are disposed thereon. Undesired rotation of the nuts 130 and 132 is prevented by cotter pins 134 and 136, respectively, which extend through holes in rod bolts 128 and engage a groove 138 in each nut. The plates 116 and 118 are provided with hollow cylindrical bearing retainers 140 and 142, respectively, which are concentric with the openings "122 and 126, respectively, and are secured to the plates by bolts 144, Bearings 146 and 148, which have concave bearing surfaces, are secured in the bearing retainers 140 and 142 respectively, and cooperate with bearings 150 and 152, respectively, on rod bolt 128, which have convex hearing surfaces. Washers 154 and 156 are disposed between the nuts 130 and 132 and the bearings 150 and 152, respectively. The plates 116 and 118, the bearing retainers 140 and 142, the bearings 146, 148, 150 and 152, the nuts 130 and 132 cooperate and serve as the means for connecting components attached to the plates 116 and 118 in proper but articulated relationship and enable the components to be moved together. The resilient member 121 serves as a resilient support and downward force transmittal means for components connected to the plates 116 and 118.

In practice, it is desirable to tighten the nuts 130 and 132 on rod bolt 128 so as to slightly compress resilient member 121 and preload bearing assembly 114 and thereby prevent undue play between associated components as the outrigger assemlby is raised and lowered.

OPERATION When outrigger assembly 16 is disposed in extended, lowered crane supporting position, the wooden cribbing 98 on the bottom of each float-enables the floats to adapt to minor surface irregularities on clock 18. The bearing assemblies 114, and particularly the resilient members 121 therein, enable all components to adjust and compensate for major irregularities and gradient variations on the dock surface as FIG. 3 shows. Thus, when outrigger assembly 16 is in crane supporting position, crane 10 is level.

Because of the type, arrangement and proportion of the components in outrigger assembly 16 for crane 10, the four locations on the transfer beams 70 and 100 at which the bearings 114 for the equalizer beams are located serve as load support or vertical force reaction points at which downward vertical forces will be equal (assuming a given load and a constant boom angle) as upper crane unit 14 is rotated and crane boom 26 is aligned with each of the points. More specifically, when boom 26 is directly over one of the four vertical reaction points described, maximum downward force is exerted at the vertical reaction point directly below the boom. However, there is absolutely no downward force exerted at the diametrically opposite vertical reaction point. The two remaining vertical reaction points trans fer forces which are less than the force exerted at the vertical reaction point directly below the boom. This distribution of forces exists, even though the center of gravity shifts as upper crane unit 14 rotates.

We claim:

1. A mobile crane comprising: a vehicle; an upper unit mounted on said vehicle and rotatable horizontally about a center of rotation, said upper unit comprising a boom pivotable about a generally horizontal axis; said vehicle and upper unit having a combined center of gravity which describes a non-circular path around said center of rotation as said upper unit rotates, assuming constant load and boom angle conditions; two pairs of horizontally spaced apart outrigger beams mounted transversely on said vehicle, each pair of outrigger beams being extendible and retractable in a generally transverse direction from the sides of said vehicle; a transfer beam rigidly connected to each pair of outrigger beams and at each of opposite sides of said vehicle and movable with the outrigger beams to a position beyond said non-circular path; a pair of equalizer beams connected to each transfer beam, each equalizer beam being connected at a vertical reaction point on said transfer beam, said reaction points being located fore and aft, respectively, from their adjacent Outrigger beams; and a pair of floats connected to each equalizer beam at points thereon which are equidistant from and on opposite sides the adjacent one of said vertical reaction points.

2. A mobile crane according to claim 1 includinga bearing assembly connected to and between each equalizer beam and its associated transfer beam and to and between each float and its associate equalizer beam.

3. A crane according to claim 2 wherein each bearing assembly comprises mechanical means for articulately connecting components, such as beams and floats associated with the bearing assembly.

4. A crane according to claim 3 wherein each bearing assembly further comprises a resilient member for transmitting forces between said components.

5. A crane according to claim 4 wherein each bearing assembly comprise a pair of vertically spaced apart attachment members for connection to associated beams and floats, wherein said resilient member comprises an elastomeric member disposed between said pair of attachment members, and wherein said articulated meattachment members comprises a hole for accommodating said rod and further comprises a concave bearing for association with a convex bearing on an end of said rod.

in i i i l 

1. A mobile crane comprising: a vehicle; an upper unit mounted on said vehicle and rotatable horizontally about a center of rotation, said upper unit comprising a boom pivotable about a generally horizontal axis; said vehicle and upper unit having a combined center of gravity which describes a non-circular path around said center of rotation as said upper unit rotates, assuming constant load and boom angle conditions; two pairs of horizontally spaced apart outrigger beams mounted transversely on said vehicle, each pair of outrigger beams being extendible and retractable in a generally transverse direction from the sides of said vehicle; a transfer beam rigidly connected to each pair of outrigger beams and at each of opposite sides of said vehicle and movable with the outrigger beams to a position beyond said noncircular path; a pair of equalizer beams connected to each transfer beam, each equalizer beam being connected at a vertical reaction point on said transfer beam, said reaction points being located fore and aft, respectively, from their adjacent outrigger beams; and a pair of floats connected to each equalizer beam at points thereon which are equidistant from and on opposite sides the adjacent one of said vertical reaction points.
 2. A mobile crane according to claim 1 including a bearing assembly connected to and between each equalizer beam and its associated transfer beam and to and between each float and its associate equalizer beam.
 3. A crane according to claim 2 wherein each bearing assembly comprises mechanical means for articulately connecting components, such as beams and floats associated with the bearing assembly.
 4. A crane according to claim 3 wherein each bearing assembly further comprises a resilient member for transmitting forces between said components.
 5. A crane according to claim 4 wherein each bearing assembly comprise a pair of vertically spaced apart attachment members for connection to associated beams and floats, wherein said resilient member comprises an elastomeric member disposed between said pair of attachment members, and wherein said articulated mechanical means is connected between said pair of attachment members.
 6. A crane according to claim 5 wherein said articulated mechanical means comprises a rod having convex bearings on each end thereof and wherein each of said attachment members comprises a hole for accommodating said rod and further comprises a concave bearing for association with a convex bearing on an end of said rod. 